This invention relates to a cigarette pack made of a multi-layered foil with at least one airtight layer, preferably aluminum foil, and at least one exterior layer of thermoplastic, particularly polyethylene, and having a pre-marked tear line in the foil for opening the pack. The invention also concerns a method and apparatus for pre-processing the foil to form the tear line.
The packaging industry has become increasingly interested in multi-layered bonded foil as a packaging material. The layers bonded together to form the foil can be profitably adapted to the technological demands of different applications. With packages designed to maintain the freshness of food and other consumables over a long period of time, bonded foils having at least one aroma or diffusion proof layer, preferably of aluminum, come into consideration. This foil layer can be supplemented by several layers of plastic, paper or similar materials. Should requirements call for the package to be heat sealed on all sides, the foil can be provided with a suitable heat bonding layer on at least one exterior side, e.g. with polyethylene which has a 110.degree. C. melting point.
In general, difficulty arises when bonded foil of the above mentioned type must be torn along a given line. This necessity arises when a totally sealed package must be opened to allow the use of the contents. In the case of cigarette and other tobacco product packs, an advantageous area of application for air tight foils, it is necessary to provide for an easily and reliably formed opening by tearing the foil. With conventional cigarette packs with an inner wrapper of tinfoil this problem does not arise because the wrapper does not need to form an airtight container, and can therefore be made in the form of a removable flap by using tear-off cuts in relation to the rest of the wrapper. Such tear-off cuts, perforations, etc., are, however, not possible with a package made of foil in the above described manner which is expected to hermetically seal the contents, because the desired seal would be thereby obviated.